View Full Version : Interaction of photon with electron
Alf P. Steinbach
Jun6-04, 04:26 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Here\'s a question that has me (a non-scientist) baffled.\n\nI\'ve read that e.g. a photon of light from Andromeda is a few meters\nwide when it finally arrives on Earth, and I can picture that as an\nelectromagnetic wave.\n\nWhen such a photon gives up its energy to an electron, which presumably\nhappens in a very short period of time and a very small region of space,\nwhat happens outside that region to cancel the "rest" of the photon?\n\n--\nA: Because it messes up the order in which people normally read text.\nQ: Why is it such a bad thing?\nA: Top-posting.\nQ: What is the most annoying thing on usenet and in e-mail?\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Here's a question that has me (a non-scientist) baffled.
I've read that e.g. a photon of light from Andromeda is a few meters
wide when it finally arrives on Earth, and I can picture that as an
electromagnetic wave.
When such a photon gives up its energy to an electron, which presumably
happens in a very short period of time and a very small region of space,
what happens outside that region to cancel the "rest" of the photon?
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
Rahul Jain
Jun13-04, 09:39 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nalfps@start.no (Alf P. Steinbach) writes:\n\n> Here\'s a question that has me (a non-scientist) baffled.\n>\n> I\'ve read that e.g. a photon of light from Andromeda is a few meters\n> wide when it finally arrives on Earth, and I can picture that as an\n> electromagnetic wave.\n\nI believe that this means that the 95% of the amplitude of the\nwavefunction is contained within a space that is a few meters wide.\n\n> When such a photon gives up its energy to an electron, which presumably\n> happens in a very short period of time and a very small region of space,\n> what happens outside that region to cancel the "rest" of the photon?\n\nThe "rest" of it doesn\'t exist. Once it has interacted with the\nelectron, its final position is "decohered" (at least according to how\nI\'d like QM to behave :) to location of the electron. IOW, the\nwavefunction, 95% of which spanned a few meters, collapsed upon\ninteraction with the electron to the value that allowed that interaction\nwith the electron.\n\n--\nRahul Jain\nrjain@nyct.net\nProfessional Software Developer, Amateur Quantum Mechanicist\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>alfps@start.no (Alf P. Steinbach) writes:
> Here's a question that has me (a non-scientist) baffled.
>
> I've read that e.g. a photon of light from Andromeda is a few meters
> wide when it finally arrives on Earth, and I can picture that as an
> electromagnetic wave.
I believe that this means that the 95% of the amplitude of the
wavefunction is contained within a space that is a few meters wide.
> When such a photon gives up its energy to an electron, which presumably
> happens in a very short period of time and a very small region of space,
> what happens outside that region to cancel the "rest" of the photon?
The "rest" of it doesn't exist. Once it has interacted with the
electron, its final position is "decohered" (at least according to how
I'd like QM to behave :) to location of the electron. IOW, the
wavefunction, 95% of which spanned a few meters, collapsed upon
interaction with the electron to the value that allowed that interaction
with the electron.
--
Rahul Jain
rjain@nyct.net
Professional Software Developer, Amateur Quantum Mechanicist
Alf P. Steinbach
Jun14-04, 03:07 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>* Rahul Jain:\n>\n> alfps@start.no (Alf P. Steinbach) writes:\n>\n> > Here\'s a question that has me (a non-scientist) baffled.\n> >\n> > I\'ve read that e.g. a photon of light from Andromeda is a few meters\n> > wide when it finally arrives on Earth, and I can picture that as an\n> > electromagnetic wave.\n>\n> I believe that this means that the 95% of the amplitude of the\n> wavefunction is contained within a space that is a few meters wide.\n>\n> > When such a photon gives up its energy to an electron, which presumably\n> > happens in a very short period of time and a very small region of space,\n> > what happens outside that region to cancel the "rest" of the photon?\n>\n> The "rest" of it doesn\'t exist. Once it has interacted with the\n> electron, its final position is "decohered" (at least according to how\n> I\'d like QM to behave :) to location of the electron. IOW, the\n> wavefunction, 95% of which spanned a few meters, collapsed upon\n> interaction with the electron to the value that allowed that interaction\n> with the electron.\n\nHow, by what mechanism, does the decoherence cancel the photon\'s\nelectromagnetic fields of Maxwell\'s equations?\n\nAnd how fast?\n\nOr is the modern view that there is no electromagnetic wave?\n\n--\nA: Because it messes up the order in which people normally read text.\nQ: Why is it such a bad thing?\nA: Top-posting.\nQ: What is the most annoying thing on usenet and in e-mail?\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>* Rahul Jain:
>
> alfps@start.no (Alf P. Steinbach) writes:
>
> > Here's a question that has me (a non-scientist) baffled.
> >
> > I've read that e.g. a photon of light from Andromeda is a few meters
> > wide when it finally arrives on Earth, and I can picture that as an
> > electromagnetic wave.
>
> I believe that this means that the 95% of the amplitude of the
> wavefunction is contained within a space that is a few meters wide.
>
> > When such a photon gives up its energy to an electron, which presumably
> > happens in a very short period of time and a very small region of space,
> > what happens outside that region to cancel the "rest" of the photon?
>
> The "rest" of it doesn't exist. Once it has interacted with the
> electron, its final position is "decohered" (at least according to how
> I'd like QM to behave :) to location of the electron. IOW, the
> wavefunction, 95% of which spanned a few meters, collapsed upon
> interaction with the electron to the value that allowed that interaction
> with the electron.
How, by what mechanism, does the decoherence cancel the photon's
electromagnetic fields of Maxwell's equations?
And how fast?
Or is the modern view that there is no electromagnetic wave?
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
Kirk Gregory Czuhai
Jun17-04, 04:10 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>alfps@start.no (Alf P. Steinbach) wrote in message news:<40cc6e69.910330906@news.individual.net>...\n > * Rahul Jain:\n> >\n> > alfps@start.no (Alf P. Steinbach) writes:\n> >\n> > > Here\'s a question that has me (a non-scientist) baffled.\n> > >\n> > > I\'ve read that e.g. a photon of light from Andromeda is a few meters\n> > > wide when it finally arrives on Earth, and I can picture that as an\n> > > electromagnetic wave.\n> >\n> > I believe that this means that the 95% of the amplitude of the\n> > wavefunction is contained within a space that is a few meters wide.\n> >\n> > > When such a photon gives up its energy to an electron, which presumably\n> > > happens in a very short period of time and a very small region of space,\n> > > what happens outside that region to cancel the "rest" of the photon?\n> >\n> > The "rest" of it doesn\'t exist. Once it has interacted with the\n> > electron, its final position is "decohered" (at least according to how\n> > I\'d like QM to behave :) to location of the electron. IOW, the\n> > wavefunction, 95% of which spanned a few meters, collapsed upon\n> > interaction with the electron to the value that allowed that interaction\n> > with the electron.\n>\n> How, by what mechanism, does the decoherence cancel the photon\'s\n> electromagnetic fields of Maxwell\'s equations?\n>\n> And how fast?\n>\n> Or is the modern view that there is no electromagnetic wave?\n\nthis is just the result of the wave-particle duality of quantum\nmechanics; i.e. if you design a measuring device to measure the\nprobability wave effects of the particles you will measure them, if\nyou localize and measure the location of an individual particle you\nwill measure its particle effect. This result follows from the\nheisenburg uncertainty principle.\nlove and peace,\n(kirk) kirk gregory czuhai\nhttp://www.altelco.net/~lovekgc/kirksresume.htm\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>alfps@start.no (Alf P. Steinbach) wrote in message news:<40cc6e69.910330906@news.individual.net>...
> * Rahul Jain:
> >
> > alfps@start.no (Alf P. Steinbach) writes:
> >
> > > Here's a question that has me (a non-scientist) baffled.
> > >
> > > I've read that e.g. a photon of light from Andromeda is a few meters
> > > wide when it finally arrives on Earth, and I can picture that as an
> > > electromagnetic wave.
> >
> > I believe that this means that the 95% of the amplitude of the
> > wavefunction is contained within a space that is a few meters wide.
> >
> > > When such a photon gives up its energy to an electron, which presumably
> > > happens in a very short period of time and a very small region of space,
> > > what happens outside that region to cancel the "rest" of the photon?
> >
> > The "rest" of it doesn't exist. Once it has interacted with the
> > electron, its final position is "decohered" (at least according to how
> > I'd like QM to behave :) to location of the electron. IOW, the
> > wavefunction, 95% of which spanned a few meters, collapsed upon
> > interaction with the electron to the value that allowed that interaction
> > with the electron.
>
> How, by what mechanism, does the decoherence cancel the photon's
> electromagnetic fields of Maxwell's equations?
>
> And how fast?
>
> Or is the modern view that there is no electromagnetic wave?
this is just the result of the wave-particle duality of quantum
mechanics; i.e. if you design a measuring device to measure the
probability wave effects of the particles you will measure them, if
you localize and measure the location of an individual particle you
will measure its particle effect. This result follows from the
heisenburg uncertainty principle.
love and peace,
(kirk) kirk gregory czuhai
http://www.altelco.net/~lovekgc/kirksresume.htm
Alf P. Steinbach
Jun27-04, 05:55 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>* Kirk Gregory Czuhai:\n> alfps@start.no (Alf P. Steinbach) wrote in message news:<40cc6e69.910330906@news.individual.net>...\n > > * Rahul Jain:\n> > >\n> > > alfps@start.no (Alf P. Steinbach) writes:\n> > >\n> > > > Here\'s a question that has me (a non-scientist) baffled.\n> > > >\n> > > > I\'ve read that e.g. a photon of light from Andromeda is a few meters\n> > > > wide when it finally arrives on Earth, and I can picture that as an\n> > > > electromagnetic wave.\n> > >\n> > > I believe that this means that the 95% of the amplitude of the\n> > > wavefunction is contained within a space that is a few meters wide.\n> > >\n> > > > When such a photon gives up its energy to an electron, which presumably\n> > > > happens in a very short period of time and a very small region of space,\n> > > > what happens outside that region to cancel the "rest" of the photon?\n> > >\n> > > The "rest" of it doesn\'t exist. Once it has interacted with the\n> > > electron, its final position is "decohered" (at least according to how\n> > > I\'d like QM to behave :) to location of the electron. IOW, the\n> > > wavefunction, 95% of which spanned a few meters, collapsed upon\n> > > interaction with the electron to the value that allowed that interaction\n> > > with the electron.\n> >\n> > How, by what mechanism, does the decoherence cancel the photon\'s\n> > electromagnetic fields of Maxwell\'s equations?\n> >\n> > And how fast?\n> >\n> > Or is the modern view that there is no electromagnetic wave?\n>\n> this is just the result of the wave-particle duality of quantum\n> mechanics; i.e. if you design a measuring device to measure the\n> probability wave effects of the particles you will measure them, if\n> you localize and measure the location of an individual particle you\n> will measure its particle effect. This result follows from the\n> heisenburg uncertainty principle.\n\nSo there is no effect on the electromagnetic wave, only on the\nprobability wave?\n\nI think that is a contradiction of preservation of mass/energy.\n\nOr, the effect on the electromagnetic wave is localized to the tiny\nregion of interaction with the electron, and the rest continues\nhappily as before?\n\nI think that could be the same kind of contradiction, but it\'s more\nslippery.\n\nOr, I think this is definitely a contradiction, in your view or in\nthe modern view the electromagnetic wave is the probability wave\nand it can collapse instantanously over large distances such as a\nmeter-wide photon from Andromeda?\n\n--\nA: Because it messes up the order in which people normally read text.\nQ: Why is it such a bad thing?\nA: Top-posting.\nQ: What is the most annoying thing on usenet and in e-mail?\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>* Kirk Gregory Czuhai:
> alfps@start.no (Alf P. Steinbach) wrote in message news:<40cc6e69.910330906@news.individual.net>...
> > * Rahul Jain:
> > >
> > > alfps@start.no (Alf P. Steinbach) writes:
> > >
> > > > Here's a question that has me (a non-scientist) baffled.
> > > >
> > > > I've read that e.g. a photon of light from Andromeda is a few meters
> > > > wide when it finally arrives on Earth, and I can picture that as an
> > > > electromagnetic wave.
> > >
> > > I believe that this means that the 95% of the amplitude of the
> > > wavefunction is contained within a space that is a few meters wide.
> > >
> > > > When such a photon gives up its energy to an electron, which presumably
> > > > happens in a very short period of time and a very small region of space,
> > > > what happens outside that region to cancel the "rest" of the photon?
> > >
> > > The "rest" of it doesn't exist. Once it has interacted with the
> > > electron, its final position is "decohered" (at least according to how
> > > I'd like QM to behave :) to location of the electron. IOW, the
> > > wavefunction, 95% of which spanned a few meters, collapsed upon
> > > interaction with the electron to the value that allowed that interaction
> > > with the electron.
> >
> > How, by what mechanism, does the decoherence cancel the photon's
> > electromagnetic fields of Maxwell's equations?
> >
> > And how fast?
> >
> > Or is the modern view that there is no electromagnetic wave?
>
> this is just the result of the wave-particle duality of quantum
> mechanics; i.e. if you design a measuring device to measure the
> probability wave effects of the particles you will measure them, if
> you localize and measure the location of an individual particle you
> will measure its particle effect. This result follows from the
> heisenburg uncertainty principle.
So there is no effect on the electromagnetic wave, only on the
probability wave?
I think that is a contradiction of preservation of mass/energy.
Or, the effect on the electromagnetic wave is localized to the tiny
region of interaction with the electron, and the rest continues
happily as before?
I think that could be the same kind of contradiction, but it's more
slippery.
Or, I think this is definitely a contradiction, in your view or in
the modern view the electromagnetic wave is the probability wave
and it can collapse instantanously over large distances such as a
meter-wide photon from Andromeda?
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
Alf P. Steinbach
Jun27-04, 05:59 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>* Kirk Gregory Czuhai:\n> alfps@start.no (Alf P. Steinbach) wrote in message news:<40cc6e69.910330906@news.individual.net>...\n > > * Rahul Jain:\n> > >\n> > > alfps@start.no (Alf P. Steinbach) writes:\n> > >\n> > > > Here\'s a question that has me (a non-scientist) baffled.\n> > > >\n> > > > I\'ve read that e.g. a photon of light from Andromeda is a few meters\n> > > > wide when it finally arrives on Earth, and I can picture that as an\n> > > > electromagnetic wave.\n> > >\n> > > I believe that this means that the 95% of the amplitude of the\n> > > wavefunction is contained within a space that is a few meters wide.\n> > >\n> > > > When such a photon gives up its energy to an electron, which presumably\n> > > > happens in a very short period of time and a very small region of space,\n> > > > what happens outside that region to cancel the "rest" of the photon?\n> > >\n> > > The "rest" of it doesn\'t exist. Once it has interacted with the\n> > > electron, its final position is "decohered" (at least according to how\n> > > I\'d like QM to behave :) to location of the electron. IOW, the\n> > > wavefunction, 95% of which spanned a few meters, collapsed upon\n> > > interaction with the electron to the value that allowed that interaction\n> > > with the electron.\n> >\n> > How, by what mechanism, does the decoherence cancel the photon\'s\n> > electromagnetic fields of Maxwell\'s equations?\n> >\n> > And how fast?\n> >\n> > Or is the modern view that there is no electromagnetic wave?\n>\n> this is just the result of the wave-particle duality of quantum\n> mechanics; i.e. if you design a measuring device to measure the\n> probability wave effects of the particles you will measure them, if\n> you localize and measure the location of an individual particle you\n> will measure its particle effect. This result follows from the\n> heisenburg uncertainty principle.\n\nSo there is no effect on the electromagnetic wave, only on the\nprobability wave?\n\nI think that is a contradiction of preservation of mass/energy.\n\nOr, the effect on the electromagnetic wave is localized to the tiny\nregion of interaction with the electron, and the rest continues\nhappily as before?\n\nI think that could be the same kind of contradiction, but it\'s more\nslippery.\n\nOr, I think this is definitely a contradiction, in your view or in\nthe modern view the electromagnetic wave is the probability wave\nand it can collapse instantanously over large distances such as a\nmeter-wide photon from Andromeda?\n\n--\nA: Because it messes up the order in which people normally read text.\nQ: Why is it such a bad thing?\nA: Top-posting.\nQ: What is the most annoying thing on usenet and in e-mail?\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>* Kirk Gregory Czuhai:
> alfps@start.no (Alf P. Steinbach) wrote in message news:<40cc6e69.910330906@news.individual.net>...
> > * Rahul Jain:
> > >
> > > alfps@start.no (Alf P. Steinbach) writes:
> > >
> > > > Here's a question that has me (a non-scientist) baffled.
> > > >
> > > > I've read that e.g. a photon of light from Andromeda is a few meters
> > > > wide when it finally arrives on Earth, and I can picture that as an
> > > > electromagnetic wave.
> > >
> > > I believe that this means that the 95% of the amplitude of the
> > > wavefunction is contained within a space that is a few meters wide.
> > >
> > > > When such a photon gives up its energy to an electron, which presumably
> > > > happens in a very short period of time and a very small region of space,
> > > > what happens outside that region to cancel the "rest" of the photon?
> > >
> > > The "rest" of it doesn't exist. Once it has interacted with the
> > > electron, its final position is "decohered" (at least according to how
> > > I'd like QM to behave :) to location of the electron. IOW, the
> > > wavefunction, 95% of which spanned a few meters, collapsed upon
> > > interaction with the electron to the value that allowed that interaction
> > > with the electron.
> >
> > How, by what mechanism, does the decoherence cancel the photon's
> > electromagnetic fields of Maxwell's equations?
> >
> > And how fast?
> >
> > Or is the modern view that there is no electromagnetic wave?
>
> this is just the result of the wave-particle duality of quantum
> mechanics; i.e. if you design a measuring device to measure the
> probability wave effects of the particles you will measure them, if
> you localize and measure the location of an individual particle you
> will measure its particle effect. This result follows from the
> heisenburg uncertainty principle.
So there is no effect on the electromagnetic wave, only on the
probability wave?
I think that is a contradiction of preservation of mass/energy.
Or, the effect on the electromagnetic wave is localized to the tiny
region of interaction with the electron, and the rest continues
happily as before?
I think that could be the same kind of contradiction, but it's more
slippery.
Or, I think this is definitely a contradiction, in your view or in
the modern view the electromagnetic wave is the probability wave
and it can collapse instantanously over large distances such as a
meter-wide photon from Andromeda?
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
Rahul Jain
Jun27-04, 06:02 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>alfps@start.no (Alf P. Steinbach) writes:\n\n> How, by what mechanism, does the decoherence cancel the photon\'s\n> electromagnetic fields of Maxwell\'s equations?\n\nThe photon IS the EM field, so I don\'t understand this question.\n\n> And how fast?\n\nWe don\'t know, or at least I don\'t.\n\n> Or is the modern view that there is no electromagnetic wave?\n\nThe EM wave is embodied in the photon itself. It is merely the\nquantization of that wave and the resulting need for that wave to\ncollapse to a point that is the major change when taking into account\nQM.\n\n--\nRahul Jain\nrjain@nyct.net\nProfessional Software Developer, Amateur Quantum Mechanicist\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>alfps@start.no (Alf P. Steinbach) writes:
> How, by what mechanism, does the decoherence cancel the photon's
> electromagnetic fields of Maxwell's equations?
The photon IS the EM field, so I don't understand this question.
> And how fast?
We don't know, or at least I don't.
> Or is the modern view that there is no electromagnetic wave?
The EM wave is embodied in the photon itself. It is merely the
quantization of that wave and the resulting need for that wave to
collapse to a point that is the major change when taking into account
QM.
--
Rahul Jain
rjain@nyct.net
Professional Software Developer, Amateur Quantum Mechanicist
Alex Green
Jun28-04, 12:10 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\n\nalfps@start.no (Alf P. Steinbach) wrote in message news:<40d29712.1313885234@news.individual.net>...\ n> * Kirk Gregory Czuhai:\n> > alfps@start.no (Alf P. Steinbach) wrote in message news:<40cc6e69.910330906@news.individual.net>...\n > > > > The "rest" of it doesn\'t exist. Once it has interacted with the\n> > > > electron, its final position is "decohered" (at least according to how\n> > > > I\'d like QM to behave :) to location of the electron. IOW, the\n> > > > wavefunction, 95% of which spanned a few meters, collapsed upon\n> > > > interaction with the electron to the value that allowed that interaction\n> > > > with the electron.\n> > >\n> > > How, by what mechanism, does the decoherence cancel the photon\'s\n> > > electromagnetic fields of Maxwell\'s equations?\n> > >\n> > > And how fast?\n> > >\n> > > Or is the modern view that there is no electromagnetic wave?\n> >\n> > this is just the result of the wave-particle duality of quantum\n> > mechanics; ....\n>\n> So there is no effect on the electromagnetic wave, only on the\n> probability wave?\n>\n> I think that is a contradiction of preservation of mass/energy.\n>\n> Or, the effect on the electromagnetic wave is localized to the tiny\n> region of interaction with the electron, and the rest continues\n> happily as before?\n>\n\nThe wave-particle duality of light begins with Einstein\'s postulate\nthat light is composed of particles with energy E=hf (where h is\nplanck\'s constant and f is the frequency). This can be extended to\ngive de Broglie\'s equation for a photon from wavelength z=c/f,\nmomentum p=h/z, energy E=hf and E=mc^2 so z=h/mc which is de Broglie\'s\nequation for a photon in algebraic form. De Broglie\'s equation is\nthoroughly \'relativistic\'.\n\nAlthough de Broglie waves are fascinating as the origin of\nSchrodinger\'s equation and demonstrate that QM is an offspring of SR\nthey have another interesting aspect. If the de Broglie equation is\nexpressed as a 4-vector* it leads to an interesting relationship\nbetween the velocity of a particle (v) and the velocity of it\'s wave\n(u):\n\nu * v = c^2\nSo x/t= c^2/v so\nt= vx/c^2\n\nThis quantity (vx/c^2) is the relativistic phase, the amount by which\nclocks go slow along the length of a moving object. If a stream of\nparticles were flashing simultaneously in their rest frame the flashes\nwould appear as a succession of waves to an observer travelling\nrelatively at v m/sec. In view of this Rindler ("Relativity", Oxford\nUniversity Press) considers that de Broglie waves are waves of\nsimultaneity.\n\nBest Wishes\n\nAlex Green\n\n\n*(4momentum=(p, E/c), the 4vector form of de Broglie\'s equation\n(p,E/c)=hf(N/u,1/c) and the 4vector expression for a wave\nL=f(N/u,1/c))\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>alfps@start.no (Alf P. Steinbach) wrote in message news:<40d29712.1313885234@news.individual.net>...
> * Kirk Gregory Czuhai:
> > alfps@start.no (Alf P. Steinbach) wrote in message news:<40cc6e69.910330906@news.individual.net>...
> > > > The "rest" of it doesn't exist. Once it has interacted with the
> > > > electron, its final position is "decohered" (at least according to how
> > > > I'd like QM to behave :) to location of the electron. IOW, the
> > > > wavefunction, 95% of which spanned a few meters, collapsed upon
> > > > interaction with the electron to the value that allowed that interaction
> > > > with the electron.
> > >
> > > How, by what mechanism, does the decoherence cancel the photon's
> > > electromagnetic fields of Maxwell's equations?
> > >
> > > And how fast?
> > >
> > > Or is the modern view that there is no electromagnetic wave?
> >
> > this is just the result of the wave-particle duality of quantum
> > mechanics; ....
>
> So there is no effect on the electromagnetic wave, only on the
> probability wave?
>
> I think that is a contradiction of preservation of mass/energy.
>
> Or, the effect on the electromagnetic wave is localized to the tiny
> region of interaction with the electron, and the rest continues
> happily as before?
>
The wave-particle duality of light begins with Einstein's postulate
that light is composed of particles with energy E=hf (where h is
planck's constant and f is the frequency). This can be extended to
give de Broglie's equation for a photon from wavelength z=c/f,
momentum p=h/z, energy E=hf and E=mc^2 so z=h/mc which is de Broglie's
equation for a photon in algebraic form. De Broglie's equation is
thoroughly 'relativistic'.
Although de Broglie waves are fascinating as the origin of
Schrodinger's equation and demonstrate that QM is an offspring of SR
they have another interesting aspect. If the de Broglie equation is
expressed as a 4-vector* it leads to an interesting relationship
between the velocity of a particle (v) and the velocity of it's wave
(u):
u * v = c^2[/itex]
So x/t= c^2/v so
[itex]t= vx/c^2
This quantity (vx/c^2) is the relativistic phase, the amount by which
clocks go slow along the length of a moving object. If a stream of
particles were flashing simultaneously in their rest frame the flashes
would appear as a succession of waves to an observer travelling
relatively at v m/sec. In view of this Rindler ("Relativity", Oxford
University Press) considers that de Broglie waves are waves of
simultaneity.
Best Wishes
Alex Green
*(4momentum=(p, E/c), the 4vector form of de Broglie's equation
(p,E/c)=hf(N/u,1/c) and the 4vector expression for a wave
L=f(N/u,1/c))
Alf P. Steinbach
Jun28-04, 12:10 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n* Rahul Jain:\n> alfps@start.no (Alf P. Steinbach) writes:\n>\n> > How, by what mechanism, does the decoherence cancel the photon\'s\n> > electromagnetic fields of Maxwell\'s equations?\n>\n> The photon IS the EM field, so I don\'t understand this question.\n\nSimply omit either "photon\'s" or "\'s electromagnetic fields"... ;-)\n\nAs I see it saying that what goes on is "decoherence" is at best only\nputting a label on it. It does not explain. So, restated using the\nfirst option:\n\n* How, by what mechanism, does the decoherence [referring to the\nearlier attempt at an explanation] cancel the electromagnetic fields\nof Maxwell\'s equations?\n\nAnd, layman that I am, I have an impression that decoherence is a global\nproperty of a large or massive enough system, not something that applies\nlocally to photon/electron interaction?\n\nAnyway, if it does,\n\n> > And how fast?\n>\n> We don\'t know, or at least I don\'t.\n>\n> > Or is the modern view that there is no electromagnetic wave?\n>\n> The EM wave is embodied in the photon itself. It is merely the\n> quantization of that wave and the resulting need for that wave to\n> collapse to a point that is the major change when taking into account\n> QM.\n\nYes, that "collapse" (and as I understand it far from everybody agree\nthat there _is_ a quantum wavefunction collapse) is precisely the\nquestion, no matter what label is put on it -- how does it work on the\nEM wave, how fast, by what mechanism; and if there is no such collapse,\nhow then does a physically extended EM wave interact with an electron?\n\n--\nA: Because it messes up the order in which people normally read text.\nQ: Why is it such a bad thing?\nA: Top-posting.\nQ: What is the most annoying thing on usenet and in e-mail?\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>* Rahul Jain:
> alfps@start.no (Alf P. Steinbach) writes:
>
> > How, by what mechanism, does the decoherence cancel the photon's
> > electromagnetic fields of Maxwell's equations?
>
> The photon IS the EM field, so I don't understand this question.
Simply omit either "photon's" or "'s electromagnetic fields"... ;-)
As I see it saying that what goes on is "decoherence" is at best only
putting a label on it. It does not explain. So, restated using the
first option:
* How, by what mechanism, does the decoherence [referring to the
earlier attempt at an explanation] cancel the electromagnetic fields
of Maxwell's equations?
And, layman that I am, I have an impression that decoherence is a global
property of a large or massive enough system, not something that applies
locally to photon/electron interaction?
Anyway, if it does,
> > And how fast?
>
> We don't know, or at least I don't.
>
> > Or is the modern view that there is no electromagnetic wave?
>
> The EM wave is embodied in the photon itself. It is merely the
> quantization of that wave and the resulting need for that wave to
> collapse to a point that is the major change when taking into account
> QM.
Yes, that "collapse" (and as I understand it far from everybody agree
that there _is_ a quantum wavefunction collapse) is precisely the
question, no matter what label is put on it -- how does it work on the
EM wave, how fast, by what mechanism; and if there is no such collapse,
how then does a physically extended EM wave interact with an electron?
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Alf P. Steinbach <alfps@start.no> writes\n>Or, I think this is definitely a contradiction, in your view or in\n>the modern view the electromagnetic wave is the probability wave\n>and it can collapse instantanously over large distances such as a\n>meter-wide photon from Andromeda?\n\nI was thinking about this the other day.\n\nWe are massive objects who, being at rest with respect to ourselves,\nmeasure ("internally") only proper time. It should not be surprising\nthat we see time as a constant in some sense. Or, put another way, we\nfollow a timelike path, which is an invariant properly of our local\nspace.\n\nIt might not be unlikely that we might fail to appreciate how other\nbodies/particles view the universe where they are travelling a different\npath, say lightlike.\n\nFor a photon emitted from andromeda there is an invariant, which is \'the\nnumber of oscillations between emission and absorption\'. All observers\nwill agree on this *number*. For light, this would be a good measure of\n\'distance\'. Proper time between emission and absorption for a photon is\nsomewhat undefined, in fact its almost a rude suggestion. However a\nphoton can measure distances by the number of oscillations required to\nreach any point and this does not tend to either zero or infinity in any\nframe but remains the same *number*. Its thus not totally unreasonable\nto imagine that this might be a nice measure of how a photon might \'see\'\ndistance.\n\nUsing this measure we no longer require a timelike link between the\nemitting atom in andromeda and the telescope on earth. The number of\noscillations emitted by the emitting atom is fixed, and in principle\nmeasurable and agreed by all observers. It will certainly be much less\nthan the number of oscillations to most of the universe. One is thus\ntempted to conclude that the emitting atom emits (in its own proper\ntime) a wavetrain which \'sees\' the universe as having a \'distance\' based\non this measure.\n\n\n--\nOz\nThis post is worth absolutely nothing and is probably fallacious.\n\nBTOPENWORLD address about to cease. DEMON address no longer in use.\n>>Use oz@farmeroz.port995.com (whitelist check on first posting)<<\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Alf P. Steinbach <alfps@start.no> writes
>Or, I think this is definitely a contradiction, in your view or in
>the modern view the electromagnetic wave is the probability wave
>and it can collapse instantanously over large distances such as a
>meter-wide photon from Andromeda?
I was thinking about this the other day.
We are massive objects who, being at rest with respect to ourselves,
measure ("internally") only proper time. It should not be surprising
that we see time as a constant in some sense. Or, put another way, we
follow a timelike path, which is an invariant properly of our local
space.
It might not be unlikely that we might fail to appreciate how other
bodies/particles view the universe where they are travelling a different
path, say lightlike.
For a photon emitted from andromeda there is an invariant, which is 'the
number of oscillations between emission and absorption'. All observers
will agree on this *number*. For light, this would be a good measure of
'distance'. Proper time between emission and absorption for a photon is
somewhat undefined, in fact its almost a rude suggestion. However a
photon can measure distances by the number of oscillations required to
reach any point and this does not tend to either zero or infinity in any
frame but remains the same *number*. Its thus not totally unreasonable
to imagine that this might be a nice measure of how a photon might 'see'
distance.
Using this measure we no longer require a timelike link between the
emitting atom in andromeda and the telescope on earth. The number of
oscillations emitted by the emitting atom is fixed, and in principle
measurable and agreed by all observers. It will certainly be much less
than the number of oscillations to most of the universe. One is thus
tempted to conclude that the emitting atom emits (in its own proper
time) a wavetrain which 'sees' the universe as having a 'distance' based
on this measure.
--
Oz
This post is worth absolutely nothing and is probably fallacious.
BTOPENWORLD address about to cease. DEMON address no longer in use.
>>Use oz@farmeroz.port995.com (whitelist check on first posting)<<
Frank Hellmann
Jun30-04, 05:36 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>> Or, I think this is definitely a contradiction, in your view or in\n> the modern view the electromagnetic wave is the probability wave\n> and it can collapse instantanously over large distances such as a\n> meter-wide photon from Andromeda?\n\nLook up the recent results of "teleporting" and atom across some\ndistance.\nIt\'s the same thing, you have one propability wave for two atoms and a\nmeassurement in the one collapses the whole wave including on the\nother side of the apparatus. These might be several meters appart, or\nreally as far as you want and can manage experimentaly.\nA meter or such is not a big deal experimentally when we are dealing\nwith photons, I\'ve recently done Bell violation experiments using\ncoherent scattering of photons as a standard textbook undergraduate\nproject.\n\n---\nfrank.\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>> Or, I think this is definitely a contradiction, in your view or in
> the modern view the electromagnetic wave is the probability wave
> and it can collapse instantanously over large distances such as a
> meter-wide photon from Andromeda?
Look up the recent results of "teleporting" and atom across some
distance.
It's the same thing, you have one propability wave for two atoms and a
meassurement in the one collapses the whole wave including on the
other side of the apparatus. These might be several meters appart, or
really as far as you want and can manage experimentaly.
A meter or such is not a big deal experimentally when we are dealing
with photons, I've recently done Bell violation experiments using
coherent scattering of photons as a standard textbook undergraduate
project.
---
frank.
Alex Green
Jun30-04, 05:38 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>alfps@start.no (Alf P. Steinbach) wrote in message .\n> ....\n> Yes, that "collapse" (and as I understand it far from everybody agree\n> that there _is_ a quantum wavefunction collapse) is precisely the\n> question, no matter what label is put on it -- how does it work on the\n> EM wave, how fast, by what mechanism; and if there is no such collapse,\n> how then does a physically extended EM wave interact with an electron?\n\nI am not sure that my post about de Broglie waves being waves of\nsimultaneity was clear enough. In the rest frame of a particle a\npropagating \'probability\' wave is equivalent to a field of particles\nturning on and off simultaneously. When an electron hits one of these\nparticles all the others can no longer be probed. You seem to be\nasking how there can be a field of particles turning on and off when\none particle carries all the energy(?).\n\nThe basic problem is how could a cloud of particles in the rest frame\nturn on and off simultaneously? Especially if the cloud is 1 metre\nacross and has been floating through space for millions of years. One\nexplanation is that the cloud has some sort of non-local, infinite\nvelocity synchronisation however this suggests that the energy content\nof the entire universe is increasing drastically at every instant as\nthe cloud grows and that the excess particles just become unobservable\nsomehow. Another possibility is that the \'cloud\' is actually one\nparticle but space-time is interconnected within the volume of the\ncloud so that the particle can interact at many different locations\nand even interfere with itself.\n\nThe first possibility is most popular at present because the second\npossibility seems to require a Euclidean metric for space-time that is\nnot supported by GR or causality. The second possibility in various\nforms has been muted (then abandoned) by physicists such as Wheeler\nand Feynman and is currently being championed by Cramer (in a form\nthat does not explicitly require a Euclidean metric).\n\nOne modification that might resurrect the second alternative is to\nsuggest that larger objects (whole \'clouds\') have some special law of\ncausality attached to them. Large objects would be subject to \'real\ntime\' and small objects would be subject to \'imaginary time\'.\n\nIntriguingly neither set of hypotheses seem to explain why the\nparticles in the cloud appear to turn on and off simultaneously and\nrhythmically in their own rest frame (where do they go?).\n\nBest Wishes\n\nAlex Green\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>alfps@start.no (Alf P. Steinbach) wrote in message .
> ....
> Yes, that "collapse" (and as I understand it far from everybody agree
> that there _is_ a quantum wavefunction collapse) is precisely the
> question, no matter what label is put on it -- how does it work on the
> EM wave, how fast, by what mechanism; and if there is no such collapse,
> how then does a physically extended EM wave interact with an electron?
I am not sure that my post about de Broglie waves being waves of
simultaneity was clear enough. In the rest frame of a particle a
propagating 'probability' wave is equivalent to a field of particles
turning on and off simultaneously. When an electron hits one of these
particles all the others can no longer be probed. You seem to be
asking how there can be a field of particles turning on and off when
one particle carries all the energy(?).
The basic problem is how could a cloud of particles in the rest frame
turn on and off simultaneously? Especially if the cloud is 1 metre
across and has been floating through space for millions of years. One
explanation is that the cloud has some sort of non-local, infinite
velocity synchronisation however this suggests that the energy content
of the entire universe is increasing drastically at every instant as
the cloud grows and that the excess particles just become unobservable
somehow. Another possibility is that the 'cloud' is actually one
particle but space-time is interconnected within the volume of the
cloud so that the particle can interact at many different locations
and even interfere with itself.
The first possibility is most popular at present because the second
possibility seems to require a Euclidean metric for space-time that is
not supported by GR or causality. The second possibility in various
forms has been muted (then abandoned) by physicists such as Wheeler
and Feynman and is currently being championed by Cramer (in a form
that does not explicitly require a Euclidean metric).
One modification that might resurrect the second alternative is to
suggest that larger objects (whole 'clouds') have some special law of
causality attached to them. Large objects would be subject to 'real
time' and small objects would be subject to 'imaginary time'.
Intriguingly neither set of hypotheses seem to explain why the
particles in the cloud appear to turn on and off simultaneously and
rhythmically in their own rest frame (where do they go?).
Best Wishes
Alex Green
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nAlex Green <dralexgreen@yahoo.co.uk> writes\n>The basic problem is how could a cloud of particles in the rest frame\n>turn on and off simultaneously? Especially if the cloud is 1 metre\n>across and has been floating through space for millions of years. One\n>explanation is that the cloud has some sort of non-local, infinite\n>velocity synchronisation however this suggests that the energy content\n>of the entire universe is increasing drastically at every instant as\n>the cloud grows and that the excess particles just become unobservable\n>somehow. Another possibility is that the \'cloud\' is actually one\n>particle but space-time is interconnected within the volume of the\n>cloud so that the particle can interact at many different locations\n>and even interfere with itself.\n\nIf you consider a pair of entangled particles as one particle,\nthen given that it appears as if ftl transmission occurs when the\nparticles become two (ie one is detected), is the above surprising?\n\n--\nOz\nThis post is worth absolutely nothing and is probably fallacious.\n\nBTOPENWORLD address about to cease. DEMON address no longer in use.\n>>Use oz@farmeroz.port995.com (whitelist check on first posting)<<\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Alex Green <dralexgreen@yahoo.co.uk> writes
>The basic problem is how could a cloud of particles in the rest frame
>turn on and off simultaneously? Especially if the cloud is 1 metre
>across and has been floating through space for millions of years. One
>explanation is that the cloud has some sort of non-local, infinite
>velocity synchronisation however this suggests that the energy content
>of the entire universe is increasing drastically at every instant as
>the cloud grows and that the excess particles just become unobservable
>somehow. Another possibility is that the 'cloud' is actually one
>particle but space-time is interconnected within the volume of the
>cloud so that the particle can interact at many different locations
>and even interfere with itself.
If you consider a pair of entangled particles as one particle,
then given that it appears as if ftl transmission occurs when the
particles become two (ie one is detected), is the above surprising?
--
Oz
This post is worth absolutely nothing and is probably fallacious.
BTOPENWORLD address about to cease. DEMON address no longer in use.
>>Use oz@farmeroz.port995.com (whitelist check on first posting)<<
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nAlf P. Steinbach <alfps@start.no> writes\n\n>Yes, that "collapse" (and as I understand it far from everybody agree\n>that there _is_ a quantum wavefunction collapse) is precisely the\n>question, no matter what label is put on it -- how does it work on the\n>EM wave, how fast, by what mechanism; and if there is no such collapse,\n>how then does a physically extended EM wave interact with an electron?\n\nIndeed a question I asked myself many years ago.\n\nStrangely nobody talks about \'inverse collapse\', that is emission.\nHow an isolated atom emits a photon seems to be \'well understood\'.\n\nNow if one is to take reversibility on board (the precise problem that\nsome people think demands collapse), then \'absorption\' of a photon by an\natom should be the precise same thing in reverse, and thus acceptable.\nSo *no* \'collapse\' is required for this interaction (although its use\nmay well be most convenient).\n\nThe problem seems to be with a quantum mechanically complex absorption,\noften concealed by a small word like \'screen\'. Now, chemists have to\ndeal regularly with qm events which are not describable precisely, but\nwhich can be described with a combination of theory and measurement.\nPretty well all spectroscopy falls into this category. More complex\ncombinations of transitions have also been mapped, the absorption of a\nphoton(s) by chlorophyll being one of the best understood and adequately\ncomplex to be used as an exemplar for a non-reversible absorption.\n\nOf course, outside a few specialists engrossed in this sort of detailed\nstudy, its much easier to say \'a bunch of photons are absorbed and a\nsugar molecule pops out\'. That is, collapse is a bag we can put all the\nstuff we don\'t want to model (or need to, or can\'t do) because ignoring\nthem doesn\'t affect the physics we wish to describe.\n\n--\nOz\nThis post is worth absolutely nothing and is probably fallacious.\n\nBTOPENWORLD address about to cease. DEMON address no longer in use.\n>>Use oz@farmeroz.port995.com (whitelist check on first posting)<<\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Alf P. Steinbach <alfps@start.no> writes
>Yes, that "collapse" (and as I understand it far from everybody agree
>that there _is_ a quantum wavefunction collapse) is precisely the
>question, no matter what label is put on it -- how does it work on the
>EM wave, how fast, by what mechanism; and if there is no such collapse,
>how then does a physically extended EM wave interact with an electron?
Indeed a question I asked myself many years ago.
Strangely nobody talks about 'inverse collapse', that is emission.
How an isolated atom emits a photon seems to be 'well understood'.
Now if one is to take reversibility on board (the precise problem that
some people think demands collapse), then 'absorption' of a photon by an
atom should be the precise same thing in reverse, and thus acceptable.
So *no* 'collapse' is required for this interaction (although its use
may well be most convenient).
The problem seems to be with a quantum mechanically complex absorption,
often concealed by a small word like 'screen'. Now, chemists have to
deal regularly with qm events which are not describable precisely, but
which can be described with a combination of theory and measurement.
Pretty well all spectroscopy falls into this category. More complex
combinations of transitions have also been mapped, the absorption of a
photon(s) by chlorophyll being one of the best understood and adequately
complex to be used as an exemplar for a non-reversible absorption.
Of course, outside a few specialists engrossed in this sort of detailed
study, its much easier to say 'a bunch of photons are absorbed and a
sugar molecule pops out'. That is, collapse is a bag we can put all the
stuff we don't want to model (or need to, or can't do) because ignoring
them doesn't affect the physics we wish to describe.
--
Oz
This post is worth absolutely nothing and is probably fallacious.
BTOPENWORLD address about to cease. DEMON address no longer in use.
>>Use oz@farmeroz.port995.com (whitelist check on first posting)<<
Alf P. Steinbach
Jul2-04, 04:33 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n* Alex Green:\n>\n> The wave-particle duality of light begins with Einstein\'s postulate\n> that light is composed of particles with energy E=hf (where h is\n> planck\'s constant and f is the frequency). This can be extended to\n> give de Broglie\'s equation for a photon from wavelength z=c/f,\n> momentum p=h/z, energy E=hf and E=mc^2 so z=h/mc\n\nHm, I see no connection to the question, and...\n\nAre you really sure that E=mc^2 is applicable to a photon? Giving\nm=hf/c^2. I always read that photons are _massless_, that is, have zero\nrest mass m?\n\nPerhaps m then represents the gravitational attraction of the photon?\n\n\n> If a stream of\n> particles were flashing simultaneously in their rest frame the flashes\n> would appear as a succession of waves to an observer travelling\n> relatively at v m/sec.\n\nYes, that\'s how relativity works, and it\'s an argument against a finite\nuniverse, but again I see no connection to the question?\n\n--\nA: Because it messes up the order in which people normally read text.\nQ: Why is it such a bad thing?\nA: Top-posting.\nQ: What is the most annoying thing on usenet and in e-mail?\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>* Alex Green:
>
> The wave-particle duality of light begins with Einstein's postulate
> that light is composed of particles with energy E=hf (where h is
> planck's constant and f is the frequency). This can be extended to
> give de Broglie's equation for a photon from wavelength z=c/f,
> momentum p=h/z, energy E=hf and E=mc^2 so z=h/mc
Hm, I see no connection to the question, and...
Are you really sure that E=mc^2 is applicable to a photon? Giving
m=hf/c^2. I always read that photons are _massless_, that is, have zero
rest mass m?
Perhaps m then represents the gravitational attraction of the photon?
> If a stream of
> particles were flashing simultaneously in their rest frame the flashes
> would appear as a succession of waves to an observer travelling
> relatively at v m/sec.
Yes, that's how relativity works, and it's an argument against a finite
universe, but again I see no connection to the question?
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
Arnold Neumaier
Jul2-04, 10:55 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nOz wrote:\n> Alf P. Steinbach <alfps@start.no> writes\n>\n>\n>>Yes, that "collapse" (and as I understand it far from everybody agree\n>>that there _is_ a quantum wavefunction collapse) is precisely the\n>>question, no matter what label is put on it -- how does it work on the\n>>EM wave, how fast, by what mechanism; and if there is no such collapse,\n>>how then does a physically extended EM wave interact with an electron?\n>\n>\n> Indeed a question I asked myself many years ago.\n>\n> Strangely nobody talks about \'inverse collapse\', that is emission.\n> How an isolated atom emits a photon seems to be \'well understood\'.\n\nEmission and absorption have nothing directly to do with collapse.\nStandard unitary dynamics produces from a pure state with a particle\nand s photons superpositions of a state with s photons and a state with\ns+-1 photons (sign depends on whether a photon is emitted or absorbed).\nThe collapse says in this situation that, instead, one observes either\nof the two, but not the superposition. This collapse happens in contact\nwith a large body (screen, counter, etc.) capable of dissipation.\n\n\nArnold Neumaier\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Oz wrote:
> Alf P. Steinbach <alfps@start.no> writes
>
>
>>Yes, that "collapse" (and as I understand it far from everybody agree
>>that there _is_ a quantum wavefunction collapse) is precisely the
>>question, no matter what label is put on it -- how does it work on the
>>EM wave, how fast, by what mechanism; and if there is no such collapse,
>>how then does a physically extended EM wave interact with an electron?
>
>
> Indeed a question I asked myself many years ago.
>
> Strangely nobody talks about 'inverse collapse', that is emission.
> How an isolated atom emits a photon seems to be 'well understood'.
Emission and absorption have nothing directly to do with collapse.
Standard unitary dynamics produces from a pure state with a particle
and s photons superpositions of a state with s photons and a state with
s+-1 photons (sign depends on whether a photon is emitted or absorbed).
The collapse says in this situation that, instead, one observes either
of the two, but not the superposition. This collapse happens in contact
with a large body (screen, counter, etc.) capable of dissipation.
Arnold Neumaier
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Arnold Neumaier <Arnold.Neumaier@univie.ac.at> writes\n\n>>Oz\n>> Strangely nobody talks about \'inverse collapse\', that is emission.\n>> How an isolated atom emits a photon seems to be \'well understood\'.\n>\n>Emission and absorption have nothing directly to do with collapse.\n>Standard unitary dynamics produces from a pure state with a particle\n>and s photons superpositions of a state with s photons and a state with\n>s+-1 photons (sign depends on whether a photon is emitted or absorbed).\n\nI am having to guess somewhat here. Am I to assume that the s photons\nare an incident beam? If so I am confused because I have been repeatedly\ntold that the number of photons in a beam (if adequately monochromatic,\nI assume) is indeterminate.\n\n>The collapse says in this situation that, instead, one observes either\n>of the two, but not the superposition. This collapse happens in contact\n>with a large body (screen, counter, etc.) capable of dissipation.\n\nSo you will have to give a more precise experimental setup for me to be\nable to give my handwavy solution.\n\nReading slightly between the lines am I to assume you have a beam of\nincident photons on an atom(s) capable of absorbing the radiation.\n\nIn this situation I would agree (assuming I understand superposition\ncorrectly) that each atom would typically be in a superposition of\n\'excited\' and \'ground state\' (here I assume the incident radiation to\nonly excite one energy level of the atom).\n\nNow, exposing my ignorance once again, I assume that experimental work\nhas shown that there is indeed a superposition of states, and not a\nstatistical mix of some excited and some ground state. In any case I\nwould *want* a superposition to be in some sense a merge of excited and\nground, else my model is in bother. How else are you to absorb a huge EM\nwave (could be microwaves) by an itsy bitsy atom only a fraction of a\nwavelength in length?\n\nUnfortunately the superposition of states is not stable. That being the\ncase its pretty hard to spot a superposition. However at a guess I would\nsuggest that one can infer it by suddenly switching off the light beam.\nI would guess three possible choices:\n\n1) A delayed fluorescence. That is the atom(s) emit a faint \'pulse\' of\nphotons after the beam should have passed through.\n\n2) A sort of \'photon capacitor\' effect, where in leading edge of the\npulse is slightly attenuated of delayed as is the trailing edge.\n\n3) An afterthought is that the speed of light in the interacting\nmolecules might be significantly less when traversing interacting atoms,\nif strongly interacting, then very slow.\n\nSo one might consider some or all of the above as examples where you\n*do* observe superposition.\n\nIf you want a dot of silver, then almost by definition, you are only\ngoing to record one state. That is a macroscopic, or \'permanent\' record\nmust of itself be produced by an irreversible reaction which of\nnecessity will enforce one state of a superposed multistate incoming\nbeam.\n\n--\nOz\nThis post is worth absolutely nothing and is probably fallacious.\n\nBTOPENWORLD address about to cease. DEMON address no longer in use.\n>>Use oz@farmeroz.port995.com (whitelist check on first posting)<<\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Arnold Neumaier <Arnold.Neumaier@univie.ac.at> writes
>>Oz
>> Strangely nobody talks about 'inverse collapse', that is emission.
>> How an isolated atom emits a photon seems to be 'well understood'.
>
>Emission and absorption have nothing directly to do with collapse.
>Standard unitary dynamics produces from a pure state with a particle
>and s photons superpositions of a state with s photons and a state with
>s+-1 photons (sign depends on whether a photon is emitted or absorbed).
I am having to guess somewhat here. Am I to assume that the s photons
are an incident beam? If so I am confused because I have been repeatedly
told that the number of photons in a beam (if adequately monochromatic,
I assume) is indeterminate.
>The collapse says in this situation that, instead, one observes either
>of the two, but not the superposition. This collapse happens in contact
>with a large body (screen, counter, etc.) capable of dissipation.
So you will have to give a more precise experimental setup for me to be
able to give my handwavy solution.
Reading slightly between the lines am I to assume you have a beam of
incident photons on an atom(s) capable of absorbing the radiation.
In this situation I would agree (assuming I understand superposition
correctly) that each atom would typically be in a superposition of
'excited' and 'ground state' (here I assume the incident radiation to
only excite one energy level of the atom).
Now, exposing my ignorance once again, I assume that experimental work
has shown that there is indeed a superposition of states, and not a
statistical mix of some excited and some ground state. In any case I
would *want* a superposition to be in some sense a merge of excited and
ground, else my model is in bother. How else are you to absorb a huge EM
wave (could be microwaves) by an itsy bitsy atom only a fraction of a
wavelength in length?
Unfortunately the superposition of states is not stable. That being the
case its pretty hard to spot a superposition. However at a guess I would
suggest that one can infer it by suddenly switching off the light beam.
I would guess three possible choices:
1) A delayed fluorescence. That is the atom(s) emit a faint 'pulse' of
photons after the beam should have passed through.
2) A sort of 'photon capacitor' effect, where in leading edge of the
pulse is slightly attenuated of delayed as is the trailing edge.
3) An afterthought is that the speed of light in the interacting
molecules might be significantly less when traversing interacting atoms,
if strongly interacting, then very slow.
So one might consider some or all of the above as examples where you
*do* observe superposition.
If you want a dot of silver, then almost by definition, you are only
going to record one state. That is a macroscopic, or 'permanent' record
must of itself be produced by an irreversible reaction which of
necessity will enforce one state of a superposed multistate incoming
beam.
--
Oz
This post is worth absolutely nothing and is probably fallacious.
BTOPENWORLD address about to cease. DEMON address no longer in use.
>>Use oz@farmeroz.port995.com (whitelist check on first posting)<<
Arnold Neumaier
Jul6-04, 01:47 PM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nOz wrote:\n> Arnold Neumaier <Arnold.Neumaier@univie.ac.at> writes\n>\n>>\n>>Emission and absorption have nothing directly to do with collapse.\n>>Standard unitary dynamics produces from a pure state with a particle\n>>and s photons superpositions of a state with s photons and a state with\n>>s+-1 photons (sign depends on whether a photon is emitted or absorbed).\n>\n> I am having to guess somewhat here. Am I to assume that the s photons\n> are an incident beam?\n\nYes. No matter how many photons, in experiments one always studies them\nas beams. The mean number of photons is just the total intensisty of\nthe beam.\nThe actual number of photons is always indeterminate since they are so\neasy to create and destroy (especially the soft = low energy photons).\n\n\n> If so I am confused because I have been repeatedly\n> told that the number of photons in a beam (if adequately monochromatic,\n> I assume) is indeterminate.\n\nThis doesn\'t depend on the color. It is impossible to create pure\ns-photon states, no matter what s is. What one can do (though it is not\neasy) to create states that are a superposition of k-photon states for\nk=0,1,2,3,... with most of the absolute amplitude square being in the\ns-particle part. This counts as an s-photon state for practical purposes.\nOn the other hand, in most experiments, one analyzes the situation for\ns-photon states and accounts at the end for the fact that one actually\nhas a superposition.\n\nThis all holds independent of \'beaminess\'. A beamlike photon is just one\nwhich has very little intensity (= mean photon number density) outside\nthe cross section of the beam.\n\n\n> In this situation I would agree (assuming I understand superposition\n> correctly) that each atom would typically be in a superposition of\n> \'excited\' and \'ground state\' (here I assume the incident radiation to\n> only excite one energy level of the atom).\n\nTypically, at the start of the experiment, the atoms are assumed to\nbe in the ground state. (Though, actually, they should be in a Gibbs\nstate describing thermal equilibrium. At low temperature, this is\nto a good approximation the ground state.)\n\nDetection of a photon means observing the\nconsequences of an excited state caused by the photon.\n\n\n> So one might consider some or all of the above as examples where you\n> *do* observe superposition.\n\nOne does not observe superpositions of observations but just one case,\nbut one computes from unitary dynamics only superpositions.\nThis is the whole measurement problem in a nutshell...\n\n\nArnold Neumaier\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Oz wrote:
> Arnold Neumaier <Arnold.Neumaier@univie.ac.at> writes
>
>>
>>Emission and absorption have nothing directly to do with collapse.
>>Standard unitary dynamics produces from a pure state with a particle
>>and s photons superpositions of a state with s photons and a state with
>>s+-1 photons (sign depends on whether a photon is emitted or absorbed).
>
> I am having to guess somewhat here. Am I to assume that the s photons
> are an incident beam?
Yes. No matter how many photons, in experiments one always studies them
as beams. The mean number of photons is just the total intensisty of
the beam.
The actual number of photons is always indeterminate since they are so
easy to create and destroy (especially the soft = low energy photons).
> If so I am confused because I have been repeatedly
> told that the number of photons in a beam (if adequately monochromatic,
> I assume) is indeterminate.
This doesn't depend on the color. It is impossible to create pure
s-photon states, no matter what s is. What one can do (though it is not
easy) to create states that are a superposition of k-photon states for
k=0,1,2,3,... with most of the absolute amplitude square being in the
s-particle part. This counts as an s-photon state for practical purposes.
On the other hand, in most experiments, one analyzes the situation for
s-photon states and accounts at the end for the fact that one actually
has a superposition.
This all holds independent of 'beaminess'. A beamlike photon is just one
which has very little intensity (= mean photon number density) outside
the cross section of the beam.
> In this situation I would agree (assuming I understand superposition
> correctly) that each atom would typically be in a superposition of
> 'excited' and 'ground state' (here I assume the incident radiation to
> only excite one energy level of the atom).
Typically, at the start of the experiment, the atoms are assumed to
be in the ground state. (Though, actually, they should be in a Gibbs
state describing thermal equilibrium. At low temperature, this is
to a good approximation the ground state.)
Detection of a photon means observing the
consequences of an excited state caused by the photon.
> So one might consider some or all of the above as examples where you
> *do* observe superposition.
One does not observe superpositions of observations but just one case,
but one computes from unitary dynamics only superpositions.
This is the whole measurement problem in a nutshell...
Arnold Neumaier
Rahul Jain
Jul13-04, 02:37 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nOz <oz@farmeroz.port995.com> writes:\n\n> Arnold Neumaier <Arnold.Neumaier@univie.ac.at> writes\n>\n>>Emission and absorption have nothing directly to do with collapse.\n>>Standard unitary dynamics produces from a pure state with a particle\n>>and s photons superpositions of a state with s photons and a state with\n>>s+-1 photons (sign depends on whether a photon is emitted or absorbed).\n>\n> I am having to guess somewhat here. Am I to assume that the s photons\n> are an incident beam? If so I am confused because I have been repeatedly\n> told that the number of photons in a beam (if adequately monochromatic,\n> I assume) is indeterminate.\n\nThe way I read Arnold\'s statement, those photons are just the photons\nthrought the entire system. Or you could take s to be 0 or 1,\nrespectively.\n\n> Now, exposing my ignorance once again, I assume that experimental work\n> has shown that there is indeed a superposition of states, and not a\n> statistical mix of some excited and some ground state.\n\nThe simplest experiment for showing superpositions of a single\nparticle\'s state is diffraction. Diffraction has been observed even in\nlarge molecules such as fullerenes, sent one at a time through the\ngrating.\n\n> Unfortunately the superposition of states is not stable.\n\nIt is stable as long as nothing else happens that causes decoherence.\nThis is how entangled particles can travel long distances coherently.\nThe more that the entangled particles experience interactions with other\nparticles, the more likely it is for that group to lose entanglement by\ndecohering.\n\n> That being the case its pretty hard to spot a superposition.\n\nObservation of a superposition causes it to decohere. It\'s a bit harder\nthan "pretty hard". :)\n\n> However at a guess I would suggest that one can infer it by suddenly\n> switching off the light beam.\n\nOne can infer superposition by noting that the observation sometimes\nrecords one state and sometimes records another. Or that a later\nobservation required the particle to be in states that interfered with\neach other.\n\n--\nRahul Jain\nrjain@nyct.net\nProfessional Software Developer, Amateur Quantum Mechanicist\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Oz <oz@farmeroz.port995.com> writes:
> Arnold Neumaier <Arnold.Neumaier@univie.ac.at> writes
>
>>Emission and absorption have nothing directly to do with collapse.
>>Standard unitary dynamics produces from a pure state with a particle
>>and s photons superpositions of a state with s photons and a state with
>>s+-1 photons (sign depends on whether a photon is emitted or absorbed).
>
> I am having to guess somewhat here. Am I to assume that the s photons
> are an incident beam? If so I am confused because I have been repeatedly
> told that the number of photons in a beam (if adequately monochromatic,
> I assume) is indeterminate.
The way I read Arnold's statement, those photons are just the photons
throught the entire system. Or you could take s to be or 1,
respectively.
> Now, exposing my ignorance once again, I assume that experimental work
> has shown that there is indeed a superposition of states, and not a
> statistical mix of some excited and some ground state.
The simplest experiment for showing superpositions of a single
particle's state is diffraction. Diffraction has been observed even in
large molecules such as fullerenes, sent one at a time through the
grating.
> Unfortunately the superposition of states is not stable.
It is stable as long as nothing else happens that causes decoherence.
This is how entangled particles can travel long distances coherently.
The more that the entangled particles experience interactions with other
particles, the more likely it is for that group to lose entanglement by
decohering.
> That being the case its pretty hard to spot a superposition.
Observation of a superposition causes it to decohere. It's a bit harder
than "pretty hard". :)
> However at a guess I would suggest that one can infer it by suddenly
> switching off the light beam.
One can infer superposition by noting that the observation sometimes
records one state and sometimes records another. Or that a later
observation required the particle to be in states that interfered with
each other.
--
Rahul Jain
rjain@nyct.net
Professional Software Developer, Amateur Quantum Mechanicist
Rahul Jain
Jul13-04, 02:37 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nOz <oz@farmeroz.port995.com> writes:\n\n> Now if one is to take reversibility on board (the precise problem that\n> some people think demands collapse), then \'absorption\' of a photon by an\n> atom should be the precise same thing in reverse, and thus acceptable.\n> So *no* \'collapse\' is required for this interaction (although its use\n> may well be most convenient).\n\nNo. In order for an event to definitely have occurred, the wave function\nof the system must collapse and go to zero where that event has not\noccurred. I don\'t see why absorption is somehow different from emission.\nEither the event has occurred or it hasn\'t. At some point we\'ll know for\nsure how decoherence works, and we\'ll be able to describe when the\n"decision" must be made.\n\n--\nRahul Jain\nrjain@nyct.net\nProfessional Software Developer, Amateur Quantum Mechanicist\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Oz <oz@farmeroz.port995.com> writes:
> Now if one is to take reversibility on board (the precise problem that
> some people think demands collapse), then 'absorption' of a photon by an
> atom should be the precise same thing in reverse, and thus acceptable.
> So *no* 'collapse' is required for this interaction (although its use
> may well be most convenient).
No. In order for an event to definitely have occurred, the wave function
of the system must collapse and go to zero where that event has not
occurred. I don't see why absorption is somehow different from emission.
Either the event has occurred or it hasn't. At some point we'll know for
sure how decoherence works, and we'll be able to describe when the
"decision" must be made.
--
Rahul Jain
rjain@nyct.net
Professional Software Developer, Amateur Quantum Mechanicist
p.kinsler@imperial.ac.uk
Jul13-04, 07:34 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nRahul Jain <rjain@nyct.net> wrote:\n\n> Oz <oz@farmeroz.port995.com> writes:\n\n> > Now if one is to take reversibility on board (the precise problem that\n> > some people think demands collapse), then \'absorption\' of a photon by an\n> > atom should be the precise same thing in reverse, and thus acceptable.\n> > So *no* \'collapse\' is required for this interaction (although its use\n> > may well be most convenient).\n\n> No. In order for an event to definitely have occurred, the wave\n> function of the system must collapse and go to zero where that\n> event has not occurred.\n\nWell, the probability amplitude of the system being in the non-\noccurred state must be zero, where that state is represented by\na wavefunction.\n\n> I don\'t see why absorption is somehow different from emission.\n> Either the event has occurred or it hasn\'t.\n\nWell, if the system was in a superpostion of occurred/non-occurred,\nthen it has neither (or both) occurred or it hasn\'t; depending\non whether you like your glasses half-full or half-empty.\n\n> At some point we\'ll know for sure how decoherence works, and\n> we\'ll be able to describe when the "decision" must be made.\n\nMathematical models, where their approximations are valid, are\nperfectly capable of telling us how the probability amplitudes of\noccurred or non-occured basis states change over time. What more do\nyou need?\n\nStop worrying about "how decoherence works". Do a calculation and\ninterpret the results in a physically sensible fashion. QM might\nbenefit from bolting on cute "decoherence" mechanisms; but since\nthey can arrive naturally as a result of not inconvenent assumptions\nand approximations, why bother? After all, I would then have 2\ndecoherence mechanisms, one supposedly "intrinsic" bolt-on to QM,\nand one arising from the nature of the system under study. How\nwould I have gained, given that there\'s no eveidence that the\nbolt-on is of any use except to satisfy philosophical confusion?\n\nHow does decoherence work? Go and learn to derive a master equation\nlike those seen in many quantum optics textbooks, and then ask some\nless vague questions! Worry about the usage of the rotating wave\napproximation, the supposedly near-constant coupling parameters, the\nspectrum of the reservior modes.\n\n--\n---------------------------------+---------------------------------\nDr. Paul Kinsler\nBlackett Laboratory (QOLS) (ph) +44-20-759-47520 (fax) 47714\nImperial College London, Dr.Paul.Kinsler@physics.org\nSW7 2BW, United Kingdom. http://www.qols.ph.ic.ac.uk/~kinsle/\n\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Rahul Jain <rjain@nyct.net> wrote:
> Oz <oz@farmeroz.port995.com> writes:
> > Now if one is to take reversibility on board (the precise problem that
> > some people think demands collapse), then 'absorption' of a photon by an
> > atom should be the precise same thing in reverse, and thus acceptable.
> > So *no* 'collapse' is required for this interaction (although its use
> > may well be most convenient).
> No. In order for an event to definitely have occurred, the wave
> function of the system must collapse and go to zero where that
> event has not occurred.
Well, the probability amplitude of the system being in the non-
occurred state must be zero, where that state is represented by
a wavefunction.
> I don't see why absorption is somehow different from emission.
> Either the event has occurred or it hasn't.
Well, if the system was in a superpostion of occurred/non-occurred,
then it has neither (or both) occurred or it hasn't; depending
on whether you like your glasses half-full or half-empty.
> At some point we'll know for sure how decoherence works, and
> we'll be able to describe when the "decision" must be made.
Mathematical models, where their approximations are valid, are
perfectly capable of telling us how the probability amplitudes of
occurred or non-occured basis states change over time. What more do
you need?
Stop worrying about "how decoherence works". Do a calculation and
interpret the results in a physically sensible fashion. QM might
benefit from bolting on cute "decoherence" mechanisms; but since
they can arrive naturally as a result of not inconvenent assumptions
and approximations, why bother? After all, I would then have 2
decoherence mechanisms, one supposedly "intrinsic" bolt-on to QM,
and one arising from the nature of the system under study. How
would I have gained, given that there's no eveidence that the
bolt-on is of any use except to satisfy philosophical confusion?
How does decoherence work? Go and learn to derive a master equation
like those seen in many quantum optics textbooks, and then ask some
less vague questions! Worry about the usage of the rotating wave
approximation, the supposedly near-constant coupling parameters, the
spectrum of the reservior modes.
--
---------------------------------+---------------------------------
Dr. Paul Kinsler
Blackett Laboratory (QOLS) (ph) +44-20-759-47520 (fax) 47714
Imperial College London, Dr.Paul.Kinsler@physics.org
SW7 2BW, United Kingdom. http://www.qols.ph.ic.ac.uk/~kinsle/
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\np.kinsler@imperial.ac.uk writes\n>Stop worrying about "how decoherence works". Do a calculation and\n>interpret the results in a physically sensible fashion. QM might\n>benefit from bolting on cute "decoherence" mechanisms; but since\n>they can arrive naturally as a result of not inconvenent assumptions\n>and approximations, why bother? After all, I would then have 2\n>decoherence mechanisms, one supposedly "intrinsic" bolt-on to QM,\n>and one arising from the nature of the system under study. How\n>would I have gained, given that there\'s no eveidence that the\n>bolt-on is of any use except to satisfy philosophical confusion?\n>\n>How does decoherence work? Go and learn to derive a master equation\n>like those seen in many quantum optics textbooks, and then ask some\n>less vague questions!\n\nI hope you already know my handwavy and mathematically imprecise model\nof how I see photons being absorbed by screen-like detectors. That is\n\'collapse\'.\n\nDespite my rather vague and imprecise model would you (doubtless with\nmany caveats) consider it \'not far off\' in principle. Its quite\nimportant to me as its one key factor in my mental model of qm. If its\nwrong, then I must find out why so I can alter my model.\n\nIts just that your recent posts seem to be saying much the same thing as\nI am (if you can stand the shame).\n\n--\nOz\nThis post is worth absolutely nothing and is probably fallacious.\n\nBTOPENWORLD address about to cease. DEMON address no longer in use.\n>>Use oz@farmeroz.port995.com<<\nozacoohdb@despammed.com still functions.\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>p.kinsler@imperial.ac.uk writes
>Stop worrying about "how decoherence works". Do a calculation and
>interpret the results in a physically sensible fashion. QM might
>benefit from bolting on cute "decoherence" mechanisms; but since
>they can arrive naturally as a result of not inconvenent assumptions
>and approximations, why bother? After all, I would then have 2
>decoherence mechanisms, one supposedly "intrinsic" bolt-on to QM,
>and one arising from the nature of the system under study. How
>would I have gained, given that there's no eveidence that the
>bolt-on is of any use except to satisfy philosophical confusion?
>
>How does decoherence work? Go and learn to derive a master equation
>like those seen in many quantum optics textbooks, and then ask some
>less vague questions!
I hope you already know my handwavy and mathematically imprecise model
of how I see photons being absorbed by screen-like detectors. That is
'collapse'.
Despite my rather vague and imprecise model would you (doubtless with
many caveats) consider it 'not far off' in principle. Its quite
important to me as its one key factor in my mental model of qm. If its
wrong, then I must find out why so I can alter my model.
Its just that your recent posts seem to be saying much the same thing as
I am (if you can stand the shame).
--
Oz
This post is worth absolutely nothing and is probably fallacious.
BTOPENWORLD address about to cease. DEMON address no longer in use.
>>Use oz@farmeroz.port995.com<<
ozacoohdb@despammed.com still functions.
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\nRahul Jain <rjain@nyct.net> writes\n\n>The simplest experiment for showing superpositions of a single\n>particle\'s state is diffraction. Diffraction has been observed even in\n>large molecules such as fullerenes, sent one at a time through the\n>grating.\n\nYes, and other experiments, you are right.\n\n>> Unfortunately the superposition of states is not stable.\n>\n>It is stable as long as nothing else happens that causes decoherence.\n\nOK, its *often* stable ....\n\n>This is how entangled particles can travel long distances coherently.\n>The more that the entangled particles experience interactions with other\n>particles, the more likely it is for that group to lose entanglement by\n>decohering.\n\nI have been taken to task for describing \'entangled\' and \'superposition\'\nin this way. I have been advised that two particles can be entangled\nwhilst one can only ever be in a superposition. However I can\'t offhand\ndisagree with your point, which is that if we are to consider particles\nas, well, particles then the superposition \'collapses\' as soon as one\nparticle is detected (assuming you diffract just one particle).\n\nOf course if one accepts (as I now do) that particles are waves, then to\nan extent the problem goes away. Only to be replaced by another of\ncourse.\n\n>> That being the case its pretty hard to spot a superposition.\n>\n>Observation of a superposition causes it to decohere. It\'s a bit harder\n>than "pretty hard". :)\n>\n>> However at a guess I would suggest that one can infer it by suddenly\n>> switching off the light beam.\n>\n>One can infer superposition by noting that the observation sometimes\n>records one state and sometimes records another. Or that a later\n>observation required the particle to be in states that interfered with\n>each other.\n\nSo, superposition can (at the very least) be \'inferred\'. I would suggest\nthat the latter example is a particularly powerful one, indeed I would\ncall it a \'detection\'.\n\nI need to move on in my model a bit. Lets just take your latter, very\ngood example and look at it in several different ways. Forgive me if I\ndon\'t have the nomenclature quite accurate (or downright wrong).\n\nWe can look at this superposed state as a solution to schroedinger. Here\nwe will have a continuous (ie analytic) wave happily time-evolving into\nits environment. Its likely a funny shape but we can plot it at any time\nover any space.\n\nNow, I *think* I have it right that we can pick out a particular basis\nwhere it looks like two particles, or better two states of one particle.\nI am tempted to move to a ket notation (which, given my level of\nignorance is dangerous) and say\n\n|f> = |a> + |b>\n\nWhere, in essence my nice continuously evolving schroedinger wave |f> is\nsplit into |a> and |b>.\n\nNow, upon reflection, its odd that this can be done. One might imagine\nthat a wave with a rather non-constant profile in space as its evolves\nwouldn\'t neatly fit into two bits each of which more or less time\nevolves in their own way precisely to match the way |f> evolves, but it\ndoes. That makes schroedinger a bit special. Without this capability, we\nwouldn\'t see the world as we do.\n\nHmmm....\nBlow me if I haven\'t come full circle. Quantumness is inherent in the\nwave equation particles follow, which is of course not remotely\nsurprising (schroedinger wouldn\'t work otherwise). So I don\'t need to\nworry about particulate quantumness at all. Its an inherent feature of\nschroedinger that an entirely wavelike description can (often) be broken\ninto two bases where each time-evolves in its own way and yet together\nthey automagically match precisely the overall (originally single-\nparticle) wavefunction.\n\nYo, that\'s really really neat.\n\nCan you give some examples where\n\n>Or that a later\n>observation required the particle to be in states that interfered with\n>each other.\n\n?\n\nPlease?\n\n--\nOz\nThis post is worth absolutely nothing and is probably fallacious.\n\nBTOPENWORLD address about to cease. DEMON address no longer in use.\n>>Use oz@farmeroz.port995.com<<\nozacoohdb@despammed.com still functions.\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Rahul Jain <rjain@nyct.net> writes
>The simplest experiment for showing superpositions of a single
>particle's state is diffraction. Diffraction has been observed even in
>large molecules such as fullerenes, sent one at a time through the
>grating.
Yes, and other experiments, you are right.
>> Unfortunately the superposition of states is not stable.
>
>It is stable as long as nothing else happens that causes decoherence.
OK, its *often* stable ....
>This is how entangled particles can travel long distances coherently.
>The more that the entangled particles experience interactions with other
>particles, the more likely it is for that group to lose entanglement by
>decohering.
I have been taken to task for describing 'entangled' and 'superposition'
in this way. I have been advised that two particles can be entangled
whilst one can only ever be in a superposition. However I can't offhand
disagree with your point, which is that if we are to consider particles
as, well, particles then the superposition 'collapses' as soon as one
particle is detected (assuming you diffract just one particle).
Of course if one accepts (as I now do) that particles are waves, then to
an extent the problem goes away. Only to be replaced by another of
course.
>> That being the case its pretty hard to spot a superposition.
>
>Observation of a superposition causes it to decohere. It's a bit harder
>than "pretty hard". :)
>
>> However at a guess I would suggest that one can infer it by suddenly
>> switching off the light beam.
>
>One can infer superposition by noting that the observation sometimes
>records one state and sometimes records another. Or that a later
>observation required the particle to be in states that interfered with
>each other.
So, superposition can (at the very least) be 'inferred'. I would suggest
that the latter example is a particularly powerful one, indeed I would
call it a 'detection'.
I need to move on in my model a bit. Lets just take your latter, very
good example and look at it in several different ways. Forgive me if I
don't have the nomenclature quite accurate (or downright wrong).
We can look at this superposed state as a solution to schroedinger. Here
we will have a continuous (ie analytic) wave happily time-evolving into
its environment. Its likely a funny shape but we can plot it at any time
over any space.
Now, I *think* I have it right that we can pick out a particular basis
where it looks like two particles, or better two states of one particle.
I am tempted to move to a ket notation (which, given my level of
ignorance is dangerous) and say
|f> = |a> + |b>
Where, in essence my nice continuously evolving schroedinger wave |f> is
split into |a> and |b>.
Now, upon reflection, its odd that this can be done. One might imagine
that a wave with a rather non-constant profile in space as its evolves
wouldn't neatly fit into two bits each of which more or less time
evolves in their own way precisely to match the way |f> evolves, but it
does. That makes schroedinger a bit special. Without this capability, we
wouldn't see the world as we do.
Hmmm....
Blow me if I haven't come full circle. Quantumness is inherent in the
wave equation particles follow, which is of course not remotely
surprising (schroedinger wouldn't work otherwise). So I don't need to
worry about particulate quantumness at all. Its an inherent feature of
schroedinger that an entirely wavelike description can (often) be broken
into two bases where each time-evolves in its own way and yet together
they automagically match precisely the overall (originally single-
particle) wavefunction.
Yo, that's really really neat.
Can you give some examples where
>Or that a later
>observation required the particle to be in states that interfered with
>each other.
?
Please?
--
Oz
This post is worth absolutely nothing and is probably fallacious.
BTOPENWORLD address about to cease. DEMON address no longer in use.
>>Use oz@farmeroz.port995.com<<
ozacoohdb@despammed.com still functions.
p.kinsler@imperial.ac.uk
Jul14-04, 10:20 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Oz <oz@farmeroz.port995.com> wrote:\n> Of course, outside a few specialists engrossed in this sort of detailed\n> study, its much easier to say \'a bunch of photons are absorbed and a\n> sugar molecule pops out\'. That is, collapse is a bag we can put all the\n> stuff we don\'t want to model (or need to, or can\'t do) because ignoring\n> them doesn\'t affect the physics we wish to describe.\n\nHmm. I don\'t want to quite agree with "collapse is a bag we can put\nall the stuff we don\'t want to model". Not because it isn\'t\n(often/sometimes) a useful strategy, but because we can do better --\nby comparing the stuff we don\'t want to model (SWDWTM) with specific\nmodels of such processes that we can model accurately. So we can\noften say something like "this SWDWTM is close enough to model X,\nwhich produces nice decoherence/ collapse-like features, so we\'ll use\nthat instead.\n\n--\n---------------------------------+---------------------------------\nDr. Paul Kinsler\nBlackett Laboratory (QOLS) (ph) +44-20-759-47520 (fax) 47714\nImperial College London, Dr.Paul.Kinsler@physics.org\nSW7 2BW, United Kingdom. http://www.qols.ph.ic.ac.uk/~kinsle/\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Oz <oz@farmeroz.port995.com> wrote:
> Of course, outside a few specialists engrossed in this sort of detailed
> study, its much easier to say 'a bunch of photons are absorbed and a
> sugar molecule pops out'. That is, collapse is a bag we can put all the
> stuff we don't want to model (or need to, or can't do) because ignoring
> them doesn't affect the physics we wish to describe.
Hmm. I don't want to quite agree with "collapse is a bag we can put
all the stuff we don't want to model". Not because it isn't
(often/sometimes) a useful strategy, but because we can do better --
by comparing the stuff we don't want to model (SWDWTM) with specific
models of such processes that we can model accurately. So we can
often say something like "this SWDWTM is close enough to model X,
which produces nice decoherence/ collapse-like features, so we'll use
that instead.
--
---------------------------------+---------------------------------
Dr. Paul Kinsler
Blackett Laboratory (QOLS) (ph) +44-20-759-47520 (fax) 47714
Imperial College London, Dr.Paul.Kinsler@physics.org
SW7 2BW, United Kingdom. http://www.qols.ph.ic.ac.uk/~kinsle/
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\np.kinsler@imperial.ac.uk writes\n\n>Hmm. I don\'t want to quite agree with "collapse is a bag we can put\n>all the stuff we don\'t want to model". Not because it isn\'t\n>(often/sometimes) a useful strategy, but because we can do better --\n>by comparing the stuff we don\'t want to model (SWDWTM) with specific\n>models of such processes that we can model accurately. So we can\n>often say something like "this SWDWTM is close enough to model X,\n>which produces nice decoherence/ collapse-like features, so we\'ll use\n>that instead.\n\nHmmm. In a way I am more interested in model x as a mechanism that\n*ought* to produce decoherence/collapselike features. Of course I don\'t\nknow if what I think is going on is acceptable physics, but it seems\nplausible to me.\n\nOnce I have a general model that at least mimics, or ought to be capable\nof mimicking, these features then I can make some sort of assessment as\nto whether its reasonable to put them in a bag and say \'I don\'t need to\nmodel this\'. Or, alternatively, that might not be a good idea in this\nparticular case because....\n\nThen I can move on to the next problem, leaving \'mechanism X\' as a more-\nor-less \'solved\' one. In principle at any rate. There are, after all, an\nawful lot of problems to deal with.\n\nIn the long sequence, over many years, of threads here I have (well, I\nthink I have anyway) learned a great deal. I feel that I at least begin\nto understand the simpler problems (always a good start). QM is such a\nfascinating conceptual enigma that must be based on experimentation, but\neven the interpretation of an experiment seems often to require some\ndetailed knowledge of the details of the experiment. Somehow the whole\npanoply has to be integrated into a coherent whole, and I still think\nits basically simple IF you can just see it right. The trouble for\nnaives like me is to figure out this new way of seeing things without\nthe maths. The maths helpfully offers excellent insight IF you fully\nunderstand it.\n\n--\nOz\nThis post is worth absolutely nothing and is probably fallacious.\n\nBTOPENWORLD address about to cease. DEMON address no longer in use.\n>>Use oz@farmeroz.port995.com<<\nozacoohdb@despammed.com still functions.\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>p.kinsler@imperial.ac.uk writes
>Hmm. I don't want to quite agree with "collapse is a bag we can put
>all the stuff we don't want to model". Not because it isn't
>(often/sometimes) a useful strategy, but because we can do better --
>by comparing the stuff we don't want to model (SWDWTM) with specific
>models of such processes that we can model accurately. So we can
>often say something like "this SWDWTM is close enough to model X,
>which produces nice decoherence/ collapse-like features, so we'll use
>that instead.
Hmmm. In a way I am more interested in model x as a mechanism that
*ought* to produce decoherence/collapselike features. Of course I don't
know if what I think is going on is acceptable physics, but it seems
plausible to me.
Once I have a general model that at least mimics, or ought to be capable
of mimicking, these features then I can make some sort of assessment as
to whether its reasonable to put them in a bag and say 'I don't need to
model this'. Or, alternatively, that might not be a good idea in this
particular case because....
Then I can move on to the next problem, leaving 'mechanism X' as a more-
or-less 'solved' one. In principle at any rate. There are, after all, an
awful lot of problems to deal with.
In the long sequence, over many years, of threads here I have (well, I
think I have anyway) learned a great deal. I feel that I at least begin
to understand the simpler problems (always a good start). QM is such a
fascinating conceptual enigma that must be based on experimentation, but
even the interpretation of an experiment seems often to require some
detailed knowledge of the details of the experiment. Somehow the whole
panoply has to be integrated into a coherent whole, and I still think
its basically simple IF you can just see it right. The trouble for
naives like me is to figure out this new way of seeing things without
the maths. The maths helpfully offers excellent insight IF you fully
understand it.
--
Oz
This post is worth absolutely nothing and is probably fallacious.
BTOPENWORLD address about to cease. DEMON address no longer in use.
>>Use oz@farmeroz.port995.com<<
ozacoohdb@despammed.com still functions.
Rahul Jain
Jul19-04, 03:09 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>\n\nOz <oz@farmeroz.port995.com> writes:\n\n> Can you give some examples where\n>\n>>Or that a later\n>>observation required the particle to be in states that interfered with\n>>each other.\n\nThe situation with fullerene self-interference. A single fullerene went\nthrough at a time. They were detected in a distribution that indicated\nthat the wavefunction had interfered with itself.\n\n--\nRahul Jain\nrjain@nyct.net\nProfessional Software Developer, Amateur Quantum Mechanicist\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Oz <oz@farmeroz.port995.com> writes:
> Can you give some examples where
>
>>Or that a later
>>observation required the particle to be in states that interfered with
>>each other.
The situation with fullerene self-interference. A single fullerene went
through at a time. They were detected in a distribution that indicated
that the wavefunction had interfered with itself.
--
Rahul Jain
rjain@nyct.net
Professional Software Developer, Amateur Quantum Mechanicist
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